Paper carriage shifting means in high speed line printers



Jan. 7, 1969 J. ELLIS ET AL 3,420,166

PAPER CARRIAGE SHIFTING MEANS IN HIGH SPEED LINE PRINTERS Filed July2'7, 1967 ouoooboouqoub uu c o u NTE R AND GATE-1 a PARATOR" A! a 1 1wen-3g COMPUTER FIG].

INVENTOR JONQJ Flt/S Joy VB Y Mari/4 ra/v E57 ATTORNEY United StatesPatent 34,343/66 US. (:1. 101--93 Int. Cl. B413 9/10 4 Claims ABSTRACTOF THE DISCLOSURE A line printer in which relative movement between apaper web and a print barrel, in a direction parallel to the axis of thebarrel, is used to increase the repertoire of characters. Adjacent bandsof characters include different character groups, e.g. upper and lowercase letters, so that a shift of one column pitch enables a character ofeither group to be printed in any particular columnar position. Thecharacter repertoire can be doubled without increasing the diameter ofthe print barrel or the operating speed of the print hammers.

Background of the invention This invention relates to printingapparatus. Printing apparatus of the kind usually referred to ason-the-fiy printers are well known. A typical on-the-fiy printer has atype barrel, which carries 120 circumferential bands of characters, andwhich rotates past a line of 120 print hammers at a speed of 1000revolutions per minute. A line of type may be printed on a paper orother recording mcleium between the barrel and the hammers during eachrevolution of the barrel. A particular character is printed in anycolumnar position on the medium by energising the print hammer for thatcolumn at the moment when the desired character is passing the printingposition.

The number of characters in each band is usually within the range 48 to64. The normal character set forming a band consists of the numerals0-9, the upper case letters A-Z and symbols such as &, etc. The printbarrel may be made so that it can be changed by the machine operator ifa difierent set of characters is required for a particular job. However,there is an increasing demand for the printing of character sets of 96to 128 characters, i.e. twice the size of these which have beengenerally available.

The incorporation of an enlarged character set requires a correspondingincrease in the circumference of the print barrel. The barrel is then ofsuch a size that the operator may find difiiculty in changing it.Furthermore, the peripheral speed of the barrel is doubled if therotational speed is maintained in order to print the same number oflines per minute. Consequently, the operating time for a print hammerwould have to be halved.

The present invention provides a printing apparatus which printsoptionally a line of characters selected from a first character set orfrom a second character set.

Summary of the invention According to the present invention, printingapparatus includes a cylindrical printing member; a plurality ofcircumferential bands of type characters on said printing member, eachband including at least some characters which are ditferent from thecharacters which are included in the bands immediately adjacent thereto;means to rotate said printing member about its longi- 3,420,166 PatentedJan. 7, 1969 ice tudinal axis; means to feed a recording medium pastsaid printing member in a direction perpendicular to said axis; a lineof print hammers mounted parallel to said axis and selectively operablein co-operation with said printing member to print lines of characterson said recording member; and means to produce relative movement betweensaid recording medium and said printing member in a direction parallelto said axis to select which characters may be printed in a particularcolumnar position in a line of characters.

Brief description of the drawings FIGURE 1 shows a diagrammatic view ofthe printing apparatus, and

FIGURE 2 shows a sectional view of a tractor mechanism forming part ofthe apparatus.

Description of the preferred embodiments Referring now to FIGURE 1 ofthe drawing, the printing apparatus includes a cylindrical printingmember or print barrel 1 which is mounted on a shaft 2 so that thebarrel 1 can be rotated about its longitudinal axis. The barrel 1carries a number of bands of characters 3 and 4, alternately, each band3 containing a first set of characters and each band 4 containing asecond set of characters. A plurality of hammers 5, each having anoperating mechanism 6, is arranged in a line parallel with the axis ofthe barrel 1. Although for the sake of clarity only four hammers 5 areshown in FIGURE 1, there is, in practice, one hammer for each individualband 3 and 4.

A record medium, which consists of a web of paper 7 on which columns ofcharacters are to be printed, is fed line-by line between the barrel 1and the hammers 5 by means of four tractors 8. The tractors 8 have pinswhich engage in perforations 9 near the edges of the web 7, two of thetractors 8 being arranged to engage the left hand edge and the other two(not visible in FIGURE 1) being arranged to engage the right hand edgeof the web 7. An inking ribbon 44 is fed between the web 7 and thebarrel 1.

The shaft 2 is rotated by an electric motor 10 so that the characters oneach band 3 and 4 are brought successively into a printing position inwhich they are facing and aligned with the hammers 5. Correctly-timedoperation of the hammer mechanisms 6 causes the web 7 and the ribbon 4to be pressed momentarily together between the operated hammers 5 andthe desired characters on the bands 3 and 4, thereby causing printing ofthe characters on the web 7.

The two upper tractors 8 are carried by shafts 11 and 12 and the towlower tractors 8 by shafts 13 and 14. The tractors 8 may be adjustedlaterally in pairs to accommodate different widths of web 7 by slidingthe tractor mechanisms 8 along the shafts 11-14.

The tractors 8 are also all movable laterally in synchr-onism todisplace the web 7 in a direction parallel to the axis of the barrel 1so that each print column lies opposite a band 3 and opposite a band 4in alternate revolutions of the barrel 1. Each hammer 5 is thereforeassociated with each adjacent column on the web 7. Referring also toFIGURE 2 of the drawing, which figure shows a section through one of thelower tractors 8, each tractor 8 includes a slide member 15 which ismounted on the shaft 14 (shaft 12 for the upper tractors), and a casing16 which is slidable on the member 15 and which holds a pair of pinwheels 17 and 18 carrying a tractor band 19. The wheel 18 rotates on aboss formed on the casing 16 and the wheel 17 rotates in a bearing 20,both wheels 17 and 18 being retained in a fixed lateral positionrelative to the casing 16. The wheel 17 is rotated by 3 the shaft 13which is splined so that the wheel 17 may slide along it.

Displacement of the casing 16, and hence the wheels 17 and 18, iseffected by a cam 21 which is rotated by the shaft 14. The cam 21engages with :a pin 22 attached to the casing 16 and displaces thecasing 16 along the slide member against the action of a spring 23. Theprofile of the cam 21 is such that the casing 16 is displaced by adistance equal to the width of each character band 3 and 4 forsubstantially half a revolution of the cam 21 and is returned to itsinitial position for substantially the other half revolution. The shafts13 and 14 are driven by the motor 10 through a belt 24 and a gearbox 25arranged to rotate the shaft 13 intermittently to give the requiredline-by-line movement of the web 7 and to rotate the shaft 14 todisplace and return the pin wheels 17 and 18 for alternate revolutionsof the barrel 1. The shafts 11 and 12 are coupled to the shafts 13 :and14 respectively, by means not shown, so that the upper tractors 8operate in synchronism with the lower tractors. An electromagneticclutch 26, operated by a clutch control 27 is provided so that drive tothe shafts 12 and 14 may be engaged or disengaged.

The hammers 5 are operated :at the correct times in the revolutions ofthe barrel 1 to print the desired characters. To accomplish the timingof the hammers 5 a plurality of identical hammer control circuits 28,one for each hammer mechanism 6, is provided. Each control circuit 28,one of which is shown in detail, includes 'a store 29, a comparator 30and an AND gate 31. The store 29 has a number of stages 32 for storinginformation representing from which line of characters on the barrel 1 acharacter is to be printed, and further stages 33 to store an indicationof which of the two columns associated with the particular hammer is tocontain the character. The information is entered into the stores 29 bya computer 45.

A slotted disc 34, carried by the shaft 2, rotates in synchronism withthe barrel 1. The disc 34 has a plurality of slots 35 corresponding tothe character positions round the bands 3 and 4. As each line ofcharacters reaches the printing position a photo cell 36, energised by alight source 37 which passes light through the corresponding slot 35,generates a signal which is passed to a counter 38. One of the slots 35is longer than the others and cooperates with a further photo cell 39and light source 40 to generate a resetting signal for the counter 38once in each revolution of the barrel 1. The count in the counter 38 atany instant therefore represents which particular line for characters isat the printing position. The comparator 30 compares the count in thecounter 38, with the information in the store 29 and, if thesecorrespond, passes a signal to one input of the AND gate 31.

The shaft 14 carries a semi-circular plate 41 which cooperates with aphoto cell 42 and alight source 43 to provide an indication of theposition of the cam 21 at any instant, and hence an indication of thelateral position of the web 7.

The comparator 30 also compares the indication from the photo cell 42with the entries in elements 33 of the store 29 and feeds a signal tothe other input of the AND gate 31 if there is correspondence. Hence ifthe particular character line which is at the printing position and thecolumn which is opposite a print hammer 5 are both in accordance withthe stored information, the hammer mechanism 6 for that hammer 5 isoperated and the character printed.

The above-mentioned displacement of the tractors 8 in pairs toaccommodate dilferent widths of web 7, may be effected by cables 46(FIGURE 2) attached to the members 15, or, alternatively by mean oflead-screws (not shown).

In one embodiment of the invention bands 3 include the usual set of typecharacters, that is, numerals 0-9, upper case letters A-Z and somesymbols. The bands 4 include another set of type characters, such as thelower case letters a-z and a further group of symbols. Thus a pair of 4:adjacent bands can include up to 128 different type characters.

It is convenient for purposes of description to designate the set oftype characters on the bands 3 as set I, and the set of type characterson the bands 4 as set II and to designate the print column positions asa, b, c, d, etc. and the bands as 3a, 4a, 3b, 4b, etc. numbering fromthe left hand side as seen in FIGURE 1. During the first revolution ofthe print barrel in a cycle, the columns a, b, c, d, etc. are alignedwith the bands 3a, 4a, 3b, 4b, etc. respectively. The web 7 is thenshifted to the right by one column position, so that print columnpositions a, b, c, d, etc. are aligned with bands 4a, 3b, 4b, 3c, etc.,during the second revolution of a cycle.

It will be assumed, as an example, that the character 21Xa are to beprinted in the column positions a, b, c, d of a line. The characters inthe positions a, b and c belong to set I, and the character in positiona belongs to set II. The print column positions a and c are aligned withbands including the characters of set I during the first revolution ofthe print barrel 1 in the cycle. At the same time, the print columnpositions b and d are aligned with bands including the characters of setII. Hence, the web 7 is 50 positioned during the first revolution thatthe required characters may be printed in the print column positions a,c and d. Accordingly, the hammers 5 for these positions are operated atthe appropriate times during the first revolution to print 2X12. Thecharacter in print column position b cannot be printed during thisrevolution because it is a character of set I and this print columnposition is aligned with a band including characters of set II.

The web 7 is now shifted to the right, so that print column position bis aligned with band 3b, which includes the characters of set I. Hence,the hammer 5 for bands 3b is operated at the appropriate time in thesecond revolution to print the character 1 in print column position b.Thus, the required group of characters is printed in one cycle of tworevolutions of the barrel 1. The characters from one set only can beprinted in the last print column position, since this position has beenmoved beyond the last bend during the second revolution of a printcycle. Hence, the number of print column positions in which charactersof both sets may be printed is one less than the number of bands.

It has been assumed in the foregoing description that the lateral shiftof the web 7 occurs between revolutions, that is, in the time betweenthe passage past the printing position of the last character of onerevolution and the first character of the next revolution. The timebetween characters may be too short to allow full movement of the web 7if the printer is operating at a speed of several hundred lines perminute. The printer operates normally in an asynchronous manner, that isa print cycle may be started at any time. If it is assumed that thecharacters in a band follow the normal sequence A, B, C, D, E, F, etc. aprint cycle might start when the character C is about to pass theprinting position. The first revolution of the barrel for that cyclewould be completed when the character B next passes the printingposition. The movement of the web 7, whether for lateral or linespacing, could then take place whilst the characters C, D and E, say,were passing the printing position. The second revolution for that printcycle would then be started as the character F is about to pass theprinting position.

Character sets in excess of 128 characters may be required in certaincircumstances, such as a printer which will print at will both Roman andCyrillic alphabets. Such extended sets may be provided by usingdifferent character sets on :a group of, say, four adjacent bands, theprint barrel carrying a number of groups of four bands. Each print cycleconsists of four revolutions, with a lateral shift of the paperoccurring at the end of each revolution. The cams 21, the plate 41, thecomparators 30 and the stores 29 would then be constructed to providethe required number of steps of web displacement.

The increase in the number of characters is obtained at the expense of areduction of the line printing speed for a given rotational speed of thebarrel 1, since each printing cycle takes two or more revolutions of thebarrel 1. This reduction in printing speed is acceptable if the extendedcharacter set is being used most of the time. However, it becomes lessacceptable as the proportion of printing which uses the standardcharacter set increases. This disadvantage may be overcome by providingoptional selection of the number of revolutions which comprise a printcycle, together with a rearrangement of the type characters within thebands. One way in which the printer may be modified is to replace someof the characters of set II with some of the characters of set I. Forexample, one set of characters which has been proposed as a standardconsists of 96 different characters. This requirement may be met if setI includes the usual 64 characters, but set H includes, say, the lettersA-Z plus six other characters of set I as well as the additional 32characters which are required to make up the total of 96 differentcharacters.

The modified printing apparatus is operated with two revolutions perprint cycle for printing the 96 character set, in a manner similar tothat already described in relation to printing the 128 character set.The letters A-Z occur in each band 3 and 4, so that they are availablefor printing in each print column position Without any lateral shift ofthe web 7. Consequently, text consisting only of these letters may beprinted in the conventional manner with only one revolution of thebarrel 1 per print cycle and no lateral web shift. Any other sub-set ofthe characters of set I may be duplicated in set II, so that, forexample, numeric printing, with the appropriate symbols, may be carriedout using one revolution per print cycle.

In a further modification of the invention, each band 3 and 4 includesall the characters of set I, together with a sub-set of the charactersof set II. For example, in the case of a 96 character set, each band haseighty characters. The 96 character set is made up of 64 characters ofset I and 32 characters of set II. The bands 3 include all thecharacters of set I and 16 of the characters of set II. The bands 4include all the characters of set I and the remaining 16 characters ofset II.

The printing apparatus may be used in the conventional manner, with oneprint cycle for each revolution of the barrel 1, to print charactersfrom set I, since these characters are included in all the bands 3 and4. The feeding of the web 7 for line spacing is carried out during thepassage of the characters of set II past the printing position. Thecharacters of set II in the bands are aligned along the print barrel.

The print cycle for printing the 96 characters repertoire consists oftwo revolutions of the barrel 1. The characters of set I will beavailable for printing in all print column positions during bothrevolutions. This allows movement of the Web 7 to be effected duringpart of the time when the characters of set I are passing the printingposition, so that no additional time is required for movement of the web7. One possible timing of web movement and printing is as follows:

1st revolution Characters 1-38 of set I pass the printing positionlinespacing movement of the web 7.

Characters 39-64 of set I pass the printing position print any of thesecharacters.

Characaters 1-16 of set II pass the printing position print any of thesecharacters.

2nd revolution Characters 1-38 of set I pass the printing position printany of these characters.

Characters 39-64 of set I pass the printing position lateral shift ofthe web 7.

Characters 17-32 of set II pass the printing position print any of thesecharacters.

It will be clear that other timing arrangements are possible whichutilise parts of the passage of the characters of set I past theprinting position for effecting movement of the web 7.

The modifications of the invention requires selective operation of thecams 21 which provide lateral shifting of the web 7, the web 7 beingshifted only if the full character repertoire is being used. The clutch26 is then selectively operated by the control 27, so that lateral shiftoccurs during a particularly revolution of the barrel 1 only if theclutch 26 is engaged during that revolution. Alternatively, the earns 21may be replaced by one or more solenoids, the armatures of which arecoupled to the tractors 8. The armatures of two or more solenoids may becoupled together through binary additive linkages in known manner toprovide several positions of lateral shift, if this is necessary.

The invention has been described in relation to a printing apparatus inwhich the web 7 is shifted laterally with respect to the barrel 1. Itwill be appreciated that the same effect is achieved if the barrel 1 ismoved axially with respect to the web 7. Hence, the invention requiresonly that there should be provision for relative movement between theweb 7 or other recording medium, and the barrel 1 in a directionparallel to the longitudinal axis of the barrel 1.

The invention is not limited to the apparatus described above, and manyvariations of the apparatus are possible without departing from thescope of the invention. For example, different print barrel and tractordriving means may be provided. Furthermore, different arrangements fortiming the operation of the print hammers may be used.

We claim:

1. A printing apparatus including a print member with a plurality ofbands of type characters corresponding to columns of a recording medium,

a printing hammer associated with each band and confronting said band ata printing position, odd bands containing one group of type characters,even bands cyclically interlaced between said odd bands and containingtype characters, some of which are diiferent from the type characters onsaid odd bands,

means to store a line of characters required to be printed,

means for indicating the characters on said odd and even bands at saidprinting position,

means for comparing said stored characters with said indications ofactual characters in said printing position and providing a signalindicating an equivalence therebetween,

means responsive to said equivalence indication for selectivelyoperating said hammers at the time in which the required characters ofsaid even and odd bands are in said printing position,

means for producing a relative movement between said printing member andsaid recording medium by one columnar position only when the fullrepertoire of characters on both bands is to be employed, saidindicating, comparing and selectively operable hammer means operatingagain to print only the remainder of said stored characters.

2. A printing apparatus including a print member with a plurality ofbands of type characters corresponding to columns of a recording medium,

a printing hammer element associated with each band and confronting saidband at a printing position,

odd bands containing one group of characters,

even bands interlaced with said odd bands and containing typecharacters, some of which are different from the type characters of saidodd bands,

means to store a line of characters to be printed,

means for indicating which characters on said odd and even bands areconfronting said printing position, means for comparing said storedcharacters with said indications of actual characters in said printingposition and providing a signal indicating an equivalence therebetween,

means responsive to said equivalence indicating signal for selectivelyoperating said hammers at the time in which the required characters ofsaid even and odd bands are in said printing position,

means for producing a relative movement between said printing member andsaid recording medium by one columnar position only when the fullrepertoire of characters on both bands is to be employed, saidindicating comparing and selectively operable hammer means operatingagain to print only the remainder of said characters,

said means to store a line of characters including a first storagesection associated with each printing hammer element efiective to storean indication of the required position of said printing member relativeto said hammer to print the stored character, and including a secondstorage section effective to store an indication of the requiredrelative lateral position of said recording medium and said printingmember for printing said desired character in a particular columnarposition,

said comparing means including a first section associated with eachprinting hammer element and operable to indicate an equivalence betweensaid actual position of said printing member and said indication of saidrequired position of said printing member, a second comparator sectionassociated with each printing hammer element operable to indicateequivalence between said actual relative lateral position of saidprinting member and said recording medium with respect to a storedindication of said actual relative position, and means including an ANDgate associ ated with each printing hammer element connected to bothsaid comparator sections for energizing each printing hammer upon firstand second comparator sections simultaneously producing said equivalenceindications.

3. An apparatus as claimed in claim 2 wherein said shifting meansinclude a clutch and clutch control means for selectively shifting saidprinting member laterally by one columnar position only when the fullrepertoire of characters is to be used, with lateral shifting onlyoccurring during engagement of said clutch.

4. A method of printing type characters on a recording medium includingthe steps of,

presenting a plurality of interlaced odd and even bands,

some of the characters of said odd bands being different from characterson said even bands, to a printing position whereby each individual bandis confronted with a printing hammer element, storing a line ofcharacters required to be printed, indicating characters on said odd andeven bands at the printing position, comparing said stored characterswith indications of actual characters in said printing position andproviding an output signal indicating an equivalence therebetween,operating said printing hammers in response to said equivalenceindicating output signal at the time in which said requred characters ofsaid even and odd bands are in said printing position, shifting saidrecording medium by one columnar position only when the full repertoireof characters on both bands is to be employed and repeating saidindicating, comparing and printing operations recited above only withrespect to the remainder of characters required to be printed.

References Cited UNITED STATES PATENTS 2,080,649 5/ 1937 Breitling101-96 3,001,469 9/1961 Davis et al. 101-93 3,114,491 12/1963 Wright197-133 X 3,154,235 10/ 1964 Hubbard 226-74 3,157,115 11/1964 West etal. 101-93 3,220,343 11/1965 Wasserman 101-93 3,322,063 5/1967 Hida etal. 101-93 3,331,316 7/1967 Bretti 101-93 WILLIAM B. PENN, PrimaryExaminer.

US. Cl. X.R. 197-133, 71

